X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fbootup.xml;h=0854b6c3165a7313006580269dfcc5d8aa389d37;hp=a596e85b70aaa567cb6522bdde6063793ab996f5;hb=a2e0337875addaf08225fbf9b231435ba12a88b5;hpb=e3d84721dc9bcf9008f72dae03ff0f7842d0bb4b diff --git a/man/bootup.xml b/man/bootup.xml index a596e85b7..0854b6c31 100644 --- a/man/bootup.xml +++ b/man/bootup.xml @@ -56,30 +56,31 @@ and hand control over to a boot loader stored on a persistent storage device. This boot loader will then invoke an OS kernel from disk (or the network). In the - Linux case this kernel (optionally) extracts and - executes an initial RAM disk image (initrd) such as - dracut8 + Linux case, this kernel (optionally) extracts and + executes an initial RAM disk image (initrd), such as + generated by + dracut8, which looks for the root file system (possibly using systemd1 for this). After the root file system is found and - mounted the initrd hands over control to the host's + mounted, the initrd hands over control to the host's system manager (such as systemd1) - stored on the OS image which is then responsible for + stored on the OS image, which is then responsible for probing all remaining hardware, mounting all necessary file systems and spawning all configured services. - On shutdown the system manager stops all + On shutdown, the system manager stops all services, unmounts all file systems (detaching the storage technologies backing them), and then (optionally) jumps back into the initrd code which unmounts/detaches the root file system and the storage - it resides on. As last step the system is powered down. + it resides on. As a last step, the system is powered down. Additional information about the system boot process may be found in - boot7. + boot7. @@ -90,7 +91,7 @@ systems, services and drivers that are necessary for operation of the system. On systemd1 - systems this process is split up in various discrete + systems, this process is split up in various discrete steps which are exposed as target units. (See systemd.target5 for detailed information about target units.) The @@ -99,17 +100,17 @@ deterministic, but still adheres to a limited amount of ordering structure. - When systemd starts up the system it will + When systemd starts up the system, it will activate all units that are dependencies of default.target (as well as recursively all dependencies of these - dependencies). Usually + dependencies). Usually, default.target is simply an alias of graphical.target or - multi-user.target depending on + multi-user.target, depending on whether the system is configured for a graphical UI or only for a text console. To enforce minimal ordering - between the units pulled in a number of well-known + between the units pulled in, a number of well-known target units are available, as listed on systemd.special7. @@ -144,7 +145,7 @@ v v | v rescue.target timers.target paths.target | sockets.target | | | | - \__________________|_________________ | ___________________/ + v |_________________ | ___________________/ \|/ v basic.target @@ -173,12 +174,17 @@ systemd1) or by symlinking default.target to them. + + timers.target is pulled-in + by basic.target asynchronously. + This allows timers units to depend on services which + become only available later in boot. Bootup in the Initial RAM Disk (initrd) The initial RAM disk implementation (initrd) can - be set up using systemd as well. In this case boot up + be set up using systemd as well. In this case, boot up inside the initrd follows the following structure. @@ -307,10 +313,10 @@ systemd-reboot.service systemd-poweroff.service systemd-halt.service syste See Also systemd1, - boot7, + boot7, systemd.special7, systemd.target5, - dracut8 + dracut8